二元高超声速进气道自起动特性试验

为了研究二元高超声速进气道的自起动特性，针对一带前掠侧板的混压式二元进气道，在来流马赫数为4和3.5状态开展了风洞试验，利用反压系统实现了进气道的起动、不起动和自起动过程.分析试验结果可知，进气道在来流马赫数为4和3.5状态均可自起动，但在来流马赫数为3.5，2°攻角状态不能自起动.当反压过大引起进气道不起动时，侧板根部均存在分离包、分离激波并引起溢流.从不起动状态进气道的流场结构看，该二元进气道的不起动属于软不起动，其机理不同于经典的自起动理论.但是试验结果表明，进气道的自起动马赫数仅略低于自起动理论值.当内压段入口马赫数低于2.5时，采用经典自起动理论估算自起动性能仍具有较高的精度. 

Self-start characteristics test of 2-D hypersonic inlet

In order to study the self-start characteristics of 2-D hypersonic inlet, a mixed compression 2-D inlet with swept side wall was tested in a wind tunnel at free stream Mach number 4 and 3.5. The start, unstart and self-start phenomenona were obtained with back pressure simulation system. Results showed that the inlet alllowed for self-start at Mach number 4 and 3.5, rather than at Mach number 3.5 with 2 degree angle of attack. With the inlet unstart by high back pressure, separated bubble and separated shock appeared on top wall near the bottom of side wall, and spillage was induced. After analysis of the phenomena and data from test, it indicated the inlet''s unstart behavior was soft, and different from classic self-start theory. But the test data showed that the self-start Mach number was lower than the value from classic self-start thoery slightly. When the Mach number of internal compression part was below 2.5, its self-start Mach number could be approximately estimated by classic self-start theory.